ABSTRACT
Candida albicans is an obligate diploid, apparently unable to undergo mating or meiosis [1,2]. Therefore, the variability afforded a sexual organism through meiotic recombination is not part of its arsenal for phenotypic variability which is apparently so essential for the success of pathogenic as well as nonpathogenic organisms. Another wayan organism can obtain phenotypic variability is through developmental programs. C. albicans and related species are capable of undergoing the bud-hypha transition, which provides them with at least two alternative growth forms [3]. The capacity to form a hypha appears to be basic to some forms of infection, and mutants that cannot form hyphae exhibit diminished virulence in a systemic model for pathogenesis [4-6]. However, two alternative growth forms do not seem to represent a great enough repertoire of phenotypic diversity to account for the extraordinary success C. albicans has had as both a pathogen and commensal [7,8]. It should therefore have been no surprise to discover that most strains of C. albicans and related species undergo spontaneous high-frequency switching between a number of general phenotypes that can be distinguished by colony morphology [9-15], and in some cases cell morphology [11,14].
